1. Field of the Invention
This invention arises in the field of processing fruits, particularly dried drupaceous fruits, to remove pits.
2. Description of the Prior Art
Drupaceous fruits, and particularly such fruits in dried, including partially dried, form, are part of a large agribusiness whose products are distributed worldwide. The appeal of these fruits arises from their high nutritional value, their appealing texture and taste, the ease with which they can be stored and carried by consumers for snacks and quick meals, and their ability to retain their nutritional value, texture and taste over extended periods of time without spoilage. The pitting of these fruits is a critical part of their processing, and reliable pitting is needed both to ensure the appeal of the fruits and to avoid injury to the consumer. For many of these fruits, industrial scale pitting is achieved by mechanical equipment in complex production lines that include a succession of stages that raise and lower both the temperature and moisture levels of the fruit to loosen the bonds between the pits and the fruit flesh, in addition to stages for cutting the fruit and extracting the pits. Variability within each of these functions, together with variations in the fruits themselves and the mechanical nature of the equipment, are potential sources of error.
The presence of pits and foreign objects in general is a concern not only in foods but also in bulk goods such as tobacco and textiles. To remove such objects and maintain acceptable quality levels of these goods, sorting systems have been developed by industrial equipment manufacturers such as Key Technology of Walla Walla, Wash., USA; BEST USA Inc., Centennial, Colo., USA; Odenburg Engineering, Inc., West Sacramento, Calif., USA; and Barco N.V., Kortrijk, Belgium. These sorters differentiate materials according to differences in the optical characteristics of the materials, such as color, light scattering, light reflection, and fluorescence emissions. Each sorting methodology has its limitations, however, and as a result these sorters tend to generate both false positives and false negatives, leading to the passage of defective product and the rejection of usable product. The use of any of these sorters, regardless of their methodology, presents a particular problem in the processing of drupes due to the tendency of pits to adhere to the flesh of the drupe.